The purpose of this 4-year project entitled "High Risk Crack Use Settings and HIV in El Salvador" is to conduct formative research on the social context of crack use and sexual risk-taking in targeted communities in the San Salvador metropolitan area. The study has the following aims: 1) To identify and describe structural differences within and across three types of low-income communities in the San Salvador metropolitan area that affect the social context of crack use and HIV risk;2) To document the range of variability in drug use sites, drug users'personal risk networks, and drug distribution systems across the three types of community;3) To examine the relationship between drug distribution systems, drug use settings and drug user networks and HIV risk;4) To estimate HIV prevalence among crack users in the San Salvador metropolitan area. Results from this study will be used to develop and explore the feasibility and acceptability of an HIV prevention intervention in collaboration with community partners that will address both community structural factors and the micro-social context of crack use and risky sex. An additional aim of the project is to increase the capacity of collaborating Salvadoran researchers to integrate qualitative, survey and network data in the conduct of research and intervention development. The proposed study will combine qualitative and quantitative research methods. In the first phase of the study we will conduct formative ethnographic research (community observations, focus groups and in-depth interviews) in nine communities (three of each type) in order to examine structural differences among the communities that may result in differences in the sites where crack is consumed and risky sex occurs, drug user roles in the drug distribution system, and drug user networks. We will use the formative ethnographic research to develop and pilot a survey instrument to measure macro-social characteristics of communities, the micro-social context of drug use, and individual-level drug use and HIV risky behaviors. In the second phase of the project we will conduct a survey with 540 crack smokers to explore variability in the micro-social context of drug use and HIV risk within and among the three community types, and to test the relationship between micro-social context of drug use and HIV risk. Additionally, we will conduct an abbreviated follow-up interview at 6 months with all survey participants in order to assess the effectiveness of different methods for tracking and retaining participants for follow-up interviews in the Salvadoran context, and demonstrate the feasibility of longitudinal research designs necessary for the rigorous evaluation of an HIV prevention intervention. In the final phase of the project, we will present the findings of the study to key stakeholders in the nine communities in order to develop a multi-level HIV prevention intervention. We will then explore the acceptability and feasibility of the intervention through focus group interviews with community leaders and crack users.